Brazilian Navy sailors recover debris from the Air France Flight 447 in the Atlantic Ocean northeast of Brazil. French investigators say the final report into the causes of the crash of Air France flight 447 will soon be published, three years after the jet went down in the mid-Atlantic killing all 228 people aboard.

The Air France Flight 447 crash, considered one of the worst aviation disasters in history, could have been avoided, a top-ranking aviation safety expert said.

"Absolutely, this accident didn't have to happen," said William Voss, the president and CEO of the Flight Safety Foundation.

BEA, the French government's official accident investigators, conducted a three-year investigation into the crash, which killed all 228 people on board, including one married couple from Louisiana, when the Airbus A330 slammed into the Atlantic Ocean off the coast of Brazil in 2009.

In the agency's final report, which was released today, investigators determined that a combination of technical failures and mistakes made by inadequately trained pilots was responsible for the crash. They recommended that pilots be better trained to manually fly commercial aircraft at high altitudes and called for stricter plane certification rules.

"Our investigation is a no-blame investigation. It is just a safety investigation," Jean-Paul Troadec, the director of BEA, told ABC News. "What appears in the crew behavior is that most probably, a different crew should have done the same action. So, we cannot blame this crew. What we can say is that most probably this crew and most crews were not prepared to face such an event."

But the report went on to say that there were at least 12 other instances where pilots encountered this issue and the flights continued normally without problems. Voss said the Air France pilots didn't seem prepared for the situation they found themselves in the night of the crash.

"[The pilots] seemed to have trouble looking past the automation they were accustomed to and not really able to continue with the old raw information that pilots used to depend on," he said. "Clearly the report shows that there was a lot of difficult communication on the flight deck, a lot of incomplete thoughts, a lot of confusion."

According to the report, a speed sensor on board the plane, called a pitot tube, stopped functioning after becoming clogged with ice at high-altitude while the plane was flying through a thunderstorm. This caused the auto-pilot to disengage and shift the controls back to the pilots. While flying in heavy turbulence, the pilots failed to properly diagnose the severity of the problem because the pitot tube, a critical piece of equipment to the aircraft, was sending inaccurate data to the cockpit, the report said. The pilots put the plane into a devastating stall and it fell rapidly from the sky, before pancake-ing into the ocean.

"Despite these persistent symptoms, the crew never understood that they were stalling and consequently never applied a recovery maneuver," the report said.

Investigators noted that there was no possibility of surviving the accident.

"The crew's failure to diagnose the stall situation and consequently a lack of inputs that would have made it possible to recover from [the accident]" was a contributing factor, it concluded.

Airbus said in a statement to ABC News that it has been working to improve the pitot tubes and is taking measures to avoid such accidents in the future. Air France also has stressed the equipment problems and insisted the pilots "acted in line with the information provided by the cockpit instruments and systems. .... The reading of the various data did not enable them to apply the appropriate action."